I’ve tried triangulating (the high poly version of my mesh and a low poly one) and it had no effect at all. The same goes for the flatten and the relax function of the loop tools /moving some vertrices manually, even triangulating and loop tools together did nothing.
In my opinion the topology does not cause this, because the small imperfections of the edge loops can’t have this huge effect.
In blender everything looks perfect and its not some magic smoothing effect, since it looks fine in wire frame mode as well.
It has to be something with the weights in UE only. But changing the weights in blender is a complete guessing game, when it looks differently in UE.
Is there a way to look into single NUMERIC vertex weights in ue / blender and compare them in order to check if UE is dropping any weights where it shouldn’t?
Another user appeared to have had similar problems some time ago: UE4 Dropping Vertex Weights - Character & Animation - Unreal Engine Forums